The MP said it was not clear whether the growing numbers gathering in Calais reflected the fact that there was more organised criminal trafficking of would-be asylum seekers.

Around 1,300 migrants are camping in Calais and making regular attempts to reach the UK.

The crisis escalated when a large group of asylum seekers charged onto the ramp of a P&O vessel on Wednesday afternoon after climbing over fences and overpowering port security staff.

But the captain closed the doors and the group was escorted away by French police armed with sub-machine guns.

Earlier this week, Calais mayor Natacha Bouchart threatened to blockade the port of Calais and called for Britain to do more to help control the migrants.

A swarm of illegal immigrants breach security at the port of Calais. Picture: Mark Salt

A Border Force spokesman said: "Security at the UK border is our priority, and we continue to strengthen it to stop those who have no right to enter the UK.

"We have already made improvements to security at Calais, working with the French authorities.

"We have, for instance, upgraded vehicle scanning equipment with the latest technology to detect people hiding in lorries and tankers and have increased the number of body detection dogs stationed at Calais.

"We will continue to bolster security, and the Home Secretary met the French Interior Minister Bernard Cazeneuve last week to discuss this important work.

"The ramps to the ferries were immediately raised when a number of migrants entered the port on Wednesday, and none of them were able to board.

"The incident was quickly brought under control and the French police apprehended all those involved. All freight vehicles inside the port at the time have been re-screened by Border Force."